Tailoring Water‐in‐DMSO Electrolyte for Ultra‐stable Rechargeable Zinc Batteries

Rechargeable zinc batteries (RZBs) are hindered by two primary challenges: instability of Zn anode and deterioration of the cathode structure in traditional aqueous electrolytes, largely attributable to the decomposition of active H2O. Here, we design and synthesize a non‐flammable water‐in‐dimethyl sulfoxide electrolyte to address these issues. X‐ray absorption spectroscopy, in situ techniques and computational simulations demonstrate that the activity of H2O in this electrolyte is extremely compressed, which not only suppresses the side reactions and increases the reversibility of Zn anode, but also diminishes the cathode dissolution and proton intercalation. The hybrid solid‐electrolyte interface (SEI), formed in situ, helps Zn‐Zn symmetric cell a prolonged lifespan exceeding 10000 h at 0.5 mA cm−2 and 600 h at a 60% discharge depth. The versatility of this electrolyte endows the Zn‐VO2 full batteries ultra‐stable cycling performance. This work provides insights into electrolyte structure‐property relationships, and facilitates the design of high‐performance RZBs.